At present, Liquid Crystal Displays (LCDs) have become mainstream display products in market due to their excellent performances and mature technologies.
As one key component in a liquid crystal display, a liquid crystal panel is mainly formed by cell alignment of a color filter substrate and an array substrate, and liquid crystal is filled between the color filter substrate and the array substrate to form a liquid crystal cell. In order that the liquid crystal panel can realize normal display, liquid crystal is required to have a function of changing the polarization state of light, that is, the polarization state of light is changed by an optical delay generated by the liquid crystal and thus bright and dark display is realized. Moreover, the function of the liquid crystal of changing the polarization state of light depends on the optical delay Δnd (where Δn is a difference between the refractivity in a slow axis direction and the refractivity in a fast axis direction of the liquid crystal and d is the thickness of the liquid crystal cell) of the liquid crystal. Ideally, the thickness d of the whole liquid crystal cell should be identical, so that the controllability and uniformity of the display effect are ensured. Therefore, the control of the thickness of the liquid crystal cell is of great importance to the liquid crystal display.
In addition, to meet the demand of market, there are more and more researches on flexible display and flexible display products, and flexible liquid crystal displays are also widely researched and tried. For flexible liquid crystal displays, one of key problems is that it is difficult to ensure the controllability and uniformity of the display effect because the thickness d of a liquid crystal cell is difficult to maintain during deflection.